It has heretofore been proposed to provide hat and cap stretchers for maintaining the shape of the crown during the wearing of the head piece. Usually such stretchers have been formed of a resilient metal ring extending around the inside of the top of the crown as in U.S. Pat. No. 1,789,604 to Slutzker of Jan. 20, 1931, U.S. Pat. No. 3,164,842 to Weinstein of Jan. 12, 1965 and U.S. Pat. No. 3,473,168 to Gallin of Oct. 21, 1969.
A similar expandable metal ring, located midway of the height of the crown is disclosed in U.S. Pat. No. 1,577,183 to Dowiarz of Mar. 16, 1926.
Also to be worn in the headpiece while the headpiece is being worn is the turnbuckle expandable attachment shown in U.S. Pat. No. 2,629,873 to Jarosenski of Mar. 3, 1953. The device of this patent is not collapsible to pocket size and while it exerts a stretch at the level of the sweatband the mechanism fills the upper portion of the hat leaving space for the head of the wearer.